U.S. patent number 7,100,848 [Application Number 10/434,149] was granted by the patent office on 2006-09-05 for fuel injection valve.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Nobutaka Ishii, Hideo Kato, Nobuaki Kobayashi, Tomoichi Misawa.
United States Patent |
7,100,848 |
Kobayashi , et al. |
September 5, 2006 |
Fuel injection valve
Abstract
A fuel injection valve of an internal combustion engine for a
vehicle is comprised of a nozzle plate which has a plurality of
nozzle holes. Fuel injection jets are injected from the nozzle
holes and collided with each other. The thickness of the nozzle
plate is equal to or greater than the diameter of the nozzle
holes.
Inventors: |
Kobayashi; Nobuaki (Gunma,
JP), Ishii; Nobutaka (Gunma, JP), Misawa;
Tomoichi (Gunma, JP), Kato; Hideo (Tochigi,
JP) |
Assignee: |
Hitachi, Ltd. (Tokyo-to,
JP)
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Family
ID: |
29586017 |
Appl.
No.: |
10/434,149 |
Filed: |
May 9, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20030222159 A1 |
Dec 4, 2003 |
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Foreign Application Priority Data
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May 30, 2002 [JP] |
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2002-157919 |
Jan 31, 2003 [JP] |
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2003-023128 |
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Current U.S.
Class: |
239/596;
239/533.12; 239/533.2; 239/556; 239/558; 239/585.1; 239/585.4;
239/598; 239/900 |
Current CPC
Class: |
F02M
51/0678 (20130101); F02M 51/0682 (20130101); F02M
61/1813 (20130101); F02M 61/1853 (20130101); Y10S
239/90 (20130101) |
Current International
Class: |
B05B
1/00 (20060101); B05B 1/30 (20060101) |
Field of
Search: |
;239/533.12,533.2,556,557,553.3,558,585.2,585.4,585.1,585.5,900,601,596 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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62-261664 |
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Nov 1987 |
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JP |
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2001-27169 |
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Jan 2001 |
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JP |
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Primary Examiner: Nguyen; Dinh Q.
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. A fuel injection valve comprising: a casing comprising a fuel
passage; a valve seat member disposed in the casing, the valve seat
member comprising a valve seat; a valve element displaceably
disposed within the casing, being in one of a rested state or a
lifted state relative to the valve seat; and a substantially flat
nozzle plate covering the valve seat, the nozzle plate comprising a
plurality of nozzle-hole sets, each of which comprises a plurality
of nozzle holes, each nozzle-hole set injecting fuel injection jets
and colliding the fuel injection jets with each other when the
valve element is lifted from the valve seat, the nozzle-hole sets
constituting two nozzle-hole-set aggregations, the two aggregation
being arranged to direct the collided fuel injection jets to two
different directions, a thickness of the substantially flat nozzle
plate being equal to or greater than a diameter of the nozzle
holes.
2. The fuel injection valve as claimed in claim 1, wherein the
thickness of the nozzle plate and the diameter of the nozzle holes
are predetermined, a ratio of the thickness of the nozzle plate to
the diameter of the nozzle holes being equal to or greater than a
value of 1.0.
3. The fuel injection valve as claimed in claim 2, wherein the
thickness of the nozzle plate and the diameter of the nozzle holes
are respectively less than or equal to a first value and greater
than or equal to a second value.
4. The fuel injection valve as claimed in claim 3, wherein the
first value is 0.33 mm and the second value is 0.05 mm.
5. The fuel injection valve as claimed in claim 1, wherein the
nozzle plate comprises six nozzle-hole sets.
6. The fuel injection valve as claimed in claim 5, wherein each
nozzle-hole set comprises two nozzle holes.
7. The fuel injection valve as claimed in claim 1, wherein the
nozzle plate comprises at least two nozzle-hole sets, each
nozzle-hole set comprising from two to four nozzle holes.
8. The fuel injection valve as claimed in claim 7, wherein the
valve element is at least partially formed from a magnetic
material, and the casing comprises electromagnetic means for
displacing the valve element to lift the valve element from the
valve seat.
9. The fuel injection valve as claimed in claim 8, wherein the
electromagnetic means comprises a plurality of elements which in
combination form a closed magnetic circuit when electrically
energized for displacing the valve element.
10. The fuel injection valve as claimed in claim 9, wherein the
plurality of elements comprises a fuel inlet pipe, a magnetic-path
forming member in contact with the fuel inlet pipe, and a valve
casing in contact with the magnetic-path forming member, the valve
casing being in contact with and housing the valve element, the
valve element being attracted to the fuel inlet pipe when the
plurality of elements is electrically energized.
11. The fuel injection valve as claimed in claim 9, wherein the
plurality of elements comprises a magnetic shaft, the magnetic
shaft comprising two magnetically separated halves, the two
magnetically separated halves being axially separated by a magnetic
reluctance portion, a connecting core in contact with the magnetic
shaft at a magnetically separated half thereof, and a yoke in
contact with the connecting core and with the magnetic shaft at
another magnetically separated half thereof the magnetic shaft
housing the valve element and a core tube for attracting the valve
element, a space existing between the valve element and the core
tube, the magnetic reluctance portion being formed at a position
coinciding with the space, the valve element being attracted to the
core tube when the plurality of elements is electrically
energized.
12. A fuel injection valve connected to an internal combustion
engine, the fuel injection valve comprising: a casing comprising a
fuel passage; a valve seat member disposed in the casing, the valve
seat member comprising a valve seat; a valve element displaceably
disposed within the casing; and a substantially flat nozzle plate
covering the valve seat, the nozzle pate plate comprising six
nozzle-hole sets, each nozzle-hole set comprising two nozzle holes,
each nozzle-hole set injecting two fuel injection jets and
colliding the two fuel injection jets with each other when the
valve element is lifted from the valve seat, the nozzle-hole sets
constituting two nozzle-hole-set aggregations, the nozzle-hole-set
aggregations being arranged to direct the collided fuel injection
jets to two different directions, a ratio between the thickness of
the nozzle plate and the diameter of the nozzle holes being equal
to or greater than a value of 1.0.
13. The fuel injection valve as claimed in claim 12, wherein a
first and second nozzle hole of each nozzle-hole set are inclined
symmetrically with respect to the Y--Y axis at a predetermined
angle, a first axis A--A and a second axis B--B of the respective
first and second nozzle holes intersecting on the Y--Y axis at a
point which is within the engine.
14. The fuel injection valve as claimed in claim 13, wherein the
nozzle-hole-set aggregations are symmetric with respect to the X--X
axis.
15. A fuel injection valve, comprising: a casing defining a fuel
passage; a valve seat member disposed in the casing, the valve seat
member defining a valve seat; a valve element displaceably disposed
in the casing; and a substantially flat nozzle plate covering the
valve seat, the nozzle plate comprising a plurality of
nozzle-hole-set aggregations which are symmetrically arranged with
respect to a center line of the nozzle plate, each of the
nozzle-hole-set aggregations comprising a plurality of nozzle-hole
sets, each of the nozzle-hole sets comprising a plurality of nozzle
holes, each nozzle-hole set injecting fuel injection jets and
colliding the fuel injection jets with each other when the valve
element is displaced so as to form a clearance between the valve
element and the valve seat, each nozzle-hole set forming a spray
pattern in the direction away from the center line of the nozzle
plate, a thickness t of the nozzle plate and a diameter d of the
nozzle holes existing in a ratio where the equation t/d.gtoreq.1.0
is satisfied.
16. The fuel injection valve as claimed in claim 15, wherein the
nozzle plate comprises two nozzle-hole-set aggregations, each
nozzle-hole-set aggregation comprising at least two nozzle-hole
sets, each nozzle-hole set comprising from two to four nozzle
holes.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection valve which is
preferably employed as a fuel injection valve of an internal
combustion engine for a vehicle.
Japanese Patent Provisional Publication 2001-27169 discloses a fuel
injection valve. Nozzle plates of this sort of injection valve
according to the related art can be divided into two groups. One
group is colliding nozzle plates, wherein nozzle holes formed in
the nozzle plate are inclined so as to collide jets of fuel ejected
from the nozzle holes. Another group is non-colliding nozzle
plates, wherein the nozzle holes are inclined so that fuel jets
ejected therefrom are not-mutually collided.
In an instance of a non-colliding nozzle plate, an injection jet of
fuel can be discharged in a wide area to promote atomization of
fuel by setting the thickness of the nozzle plate smaller than the
diameter of the nozzle holes.
SUMMARY OF THE INVENTION
However, in an instance of a colliding nozzle plate, if the
thickness of the nozzle plate is set smaller than the diameter of
the nozzle holes, the shorter the length of the nozzle holes
becomes, the less the injection jets of fuel from each nozzle tend
to travel in a straight line. Thus, the jets from each nozzle hole
do not properly collide, and it is difficult to promote atomization
of the fuel.
It is therefore an object of the present invention to provide a
fuel injection valve which is capable of promoting atomization of
injected fuel from a colliding nozzle plate.
An aspect of the present invention resides in a fuel injection
valve comprising a casing comprising a fuel passage, a valve seat
member disposed in the casing, the valve seat member comprising a
valve seat, a valve element displaceably disposed within the
casing, normally resting on the valve seat, and a nozzle plate
covering the valve seat, the nozzle plate comprising a plurality of
nozzle-hole sets, each of which comprises a plurality of nozzle
holes, each nozzle-hole set injecting fuel injection jets and
colliding the fuel injection jets with each other when the valve
element is lifted from the valve seat, a thickness of the nozzle
plate being equal to or greater than a diameter of the nozzle
holes.
Another aspect of the present invention resides in a fuel injection
valve connected to an internal combustion engine, the fuel
injection valve comprising a casing comprising a fuel passage, a
valve seat member disposed in the casing, the valve seat member
comprising a valve seat, a valve element displaceably disposed
within the casing; and a nozzle plate covering the valve seat, the
nozzle pate comprising six nozzle-hole sets, each nozzle-hole set
comprising two nozzle holes, each nozzle-hole set injecting two
fuel injection jets and colliding the two fuel injection jets with
each other when the valve element is lifted from the valve seat,
the nozzle-hole sets constituting two nozzle-hole-set aggregations,
the nozzle-hole-set aggregations being arranged to direct the
collided fuel injection jets to two different directions, a ratio
between the thickness of the nozzle plate and the diameter of the
nozzle holes being equal to or greater than a value of 1.0.
A further aspect of the present invention resides in a fuel
injection valve, comprising a casing defining a fuel passage, a
valve seat member disposed in the casing, the valve seat member
defining a valve seat, a valve element displaceably disposed in the
casing, and a nozzle plate covering the valve seat, the nozzle
plate comprising a plurality of nozzle-hole-set aggregations which
are symmetrically arranged with respect to a center line of the
nozzle plate, each of the nozzle-hole-set aggregations comprising a
plurality of nozzle-hole sets, each of the nozzle-hole sets
comprising a plurality of nozzle holes, each nozzle-hole set
injecting fuel injection jets and colliding the fuel injection jets
with each other when the valve element is displaced so as to form a
clearance between the valve element and the valve seat, each
nozzle-hole set forming a spray pattern in the direction away from
the center line of the nozzle plate, a thickness t of the nozzle
plate and a diameter d of the nozzle holes existing in a ratio
where the equation t/d.gtoreq.1.0 is satisfied.
The other objects and features of this invention will become
understood from the following description with reference to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view showing a fuel injection valve
according to a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of an end of a valve
casing in FIG. 1.
FIG. 3 is a cross-sectional view showing only a nozzle plate found
in FIG. 2.
FIG. 4 is a top view showing only the nozzle plate of FIG. 3.
FIG. 5 is an enlarged view showing nozzle-hole sets found in FIG. 4
enlarged together during an injection operation.
FIG. 6 is an enlarged cross-sectional view showing a pair of nozzle
holes constituting a nozzle-hole set, in the direction of the
arrows VI--VI found in FIG. 5.
FIG. 7 is an enlarged cross-sectional view showing a non-colliding
nozzle plate and constituent nozzle holes in the same manner as in
FIG. 6.
FIG. 8 is a graph showing a relationship between droplet diameter
of injected fuel and dimensional ratio between nozzle plate
thickness and nozzle hole diameter, characteristic of colliding and
non-colliding nozzle plates.
FIG. 9 is a cross-sectional view showing a fuel injection valve
according to a second embodiment of the present invention.
FIG. 10 is an enlarged cross-sectional view showing an end of an
electromagnetic tubular body found in FIG. 9.
FIG. 11 is a cross-sectional view showing only the nozzle plate in
FIG. 10.
FIG. 12 is a plan view showing only the nozzle plate.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 through 8, there is discussed a first
embodiment of a fuel injection valve applied to an internal
combustion engine for a vehicle in accordance with the present
invention.
A casing 1, which is substantially tubular, constitutes a main body
portion of a fuel injection valve. Casing 1 comprises a valve
casing 2, a fuel inlet pipe 3, and a magnetic-path forming member
5.
Valve casing 2, which is step-shaped, is disposed at an end of
casing 1, and is made of a magnetic material such as
electromagnetic stainless steel. Valve casing 2 comprises a
large-diameter tube portion 2A and a small-diameter tube portion 2B
which is formed integrally with large-diameter tube portion 2A at
an end thereof. A resin cover 14 is attached to a base of
large-diameter portion 2A.
Fuel inlet pipe 3 is formed as a tube from magnetic material such
as electromagnetic stainless steel, and is joined to a base of
valve casing 2 by a tubular joining member 4 made of non-magnetic
material. Fuel inlet pipe 3 is magnetically connected with valve
casing 2 by magnetic-path forming member 5. Magnetic-path forming
member 5 is a narrow piece of magnetic metal disposed on an outer
circumference of an electromagnetic coil 13.
Thus, when electromagnetic coil 13 is electrically energized, it is
possible to form a closed magnetic circuit with valve casing 2,
fuel inlet pipe 3, magnetic-path forming member 5, and an
attraction portion 11 of a valve element 9. A fuel passage 6 which
extends axially from the base of fuel inlet pipe 3 as far as a
valve seat member 8 within valve casing 2, and a fuel filter 7 to
filter fuel supplied to fuel passage 6 are disposed within casing
1.
A valve seat member 8 is inserted within small diameter tube
portion 2B of valve casing 2. Valve seat member 8 is formed from
metallic or plastic material, and is tubular as can be seen from
FIG. 2. A valve element insertion hole 8A is defined in an inner
circumference at the base of valve seat member 8. A substantially
conic valve seat 8B is formed at an end of valve element insertion
hole 8A, and defines a circular injection opening 8C.
Valve element 9 is displaceably disposed within valve casing 2, and
comprises a valve shaft 10 formed by bending a material such as
metal plate into a tube-shape, attraction portion 11 which is
formed into a tubular shape from a magnetic or similar material and
fixed to the base of valve shaft 10, and a valve portion 12 which
is spherical and rests on and lifts from valve seat 8B of valve
seat portion 8. A plurality of depression portions 12A are formed
on the outer circumference of valve portion 12 to form spaces
between valve portion 12 and the inner circumference of valve seat
member 8 as shown in FIGS. 1 and 2.
When valve element 9 closes to prevent flow of fuel, valve portion
12 is held in a rested state upon valve seat 8B of valve seat
member 8 due to a spring force of valve spring 16, and in this
state, attraction portion 11 and fuel inlet pipe 3 are separated by
a space along a common axis. When electromagnetic coil 13 is
electrically energized, a magnetic field is generated by
electromagnetic coil 13, and attraction portion 11 of valve element
9 is magnetically attracted by fuel inlet pipe 3. Valve element 9
displaces axially against the spring force of valve spring 16, and
valve portion 12 lifts from valve seat 8B, resulting in the valve
opening.
Electromagnetic coil 13 is disposed on an outer circumference of
fuel inlet pipe 3 as an actuator, and is covered by resin cover 14,
which is fixed from valve casing 2 to fuel inlet pipe 3 as shown in
FIG. 1. A magnetic field is generated by energizing electromagnetic
coil 13 through a connector 15 disposed on resin cover 14, and
valve element 9 is made to open.
Valve spring 16 is located within fuel inlet pipe 3 in a compressed
form. Valve spring 16 is disposed between valve element 9 and a
tubular element 17 which is fixed within fuel inlet pipe 3, and
applies force to valve element 9 in the direction of valve seat
member 8 to hold the valve in a closed position. When valve element
9 opens against the spring force of valve spring 16, fuel inside
fuel passage 6 is divergently injected left and right from nozzle
plate 18 into an intake manifold or similar area.
Nozzle plate 18 covers injection opening 8C of valve seat member 8
on an outer side injection opening 8C. As shown in FIGS. 2 through
4, nozzle plate 18 comprises a flat portion 18A formed as a
circular plate, which could be achieved through the pressing of
metal plate, and a rim portion 18B which is formed in a substantial
L-shape on an outer circumference of flat portion 18A.
Flat portion 18A is joined to an end of valve seat portion 8 by a
welding portion 19, and rim portion 18B is joined to an inner
circumference of small diameter tube portion 2B of valve casing 2
by a welding portion 20.
A plurality of nozzle holes 21 is disposed on flat portion 18A of
nozzle plate 18. Referring to FIGS. 4 and 5, a total of 12 holes
are formed in a center area of flat portion 18A, and fuel inside
casing 1 is ejected from each nozzle hole when valve element 9
opens.
Each nozzle hole 21 comprises two adjacent nozzle holes 21A and 21B
to constitute a nozzle-hole set 22, 23, 24, 25, 26, 27, there being
six nozzle-hole sets. An axis X--X runs through nozzle plate 18 to
divide nozzle plate 18 into two symmetrical halves, and divides the
nozzle-hole sets into two groups of three sets each, with
nozzle-hole sets 22, 23 and 24 on one side and nozzle-hole sets 25,
26 and 27 disposed symmetrically thereto on the other side.
As shown in FIG. 6, respective hole centers A--A and B--B of nozzle
holes 21A and 21B constituting each nozzle-hole set 22 through 27
are inclined by an angle .theta. with respect to an axis Y--Y which
is orthogonal to flat portion 18A of nozzle plate 18. Hole centers
A--A and B--B intersect to form a V-shape centered about axis
Y--Y.
Thus, each nozzle set 22 through 27 is formed as a colliding
nozzle-hole set which collides injection jets of fuel injected from
respective nozzle holes 21A and 21B in the directions designated by
F.
Nozzle-hole sets 22 through 27 atomize fuel by colliding injection
jets of fuel discharged from nozzle holes 21A and 21B into each
other, and discharge fuel in the spray patterns 28, 29, 30, 31, 32,
and 33 shown in FIG. 5.
A plate thickness t of nozzle plate 18 (flat portion 18A) and a
hole diameter d of nozzle holes 21A and 21B exist in a dimensional
ratio t/d where the following expression (1) is satisfied.
t/d.gtoreq.1.0 (1)
According to this first embodiment, plate thickness t of nozzle
plate 18 is set within a range 0.3 mm.gtoreq.t.gtoreq.0.05 mm, and
hole diameter d of each nozzle hole 21A, 21B is set within a range
0.3 mm.gtoreq.d.gtoreq.0.05 mm as can be seen in FIG. 6.
Thus, it is possible to set a length L of nozzle holes 21A and 21B
formed in nozzle plate 18 to be long, and to maintain the ability
of injection jets to travel in a straight line when the injection
jets are discharged from respective nozzle holes 21A and 21B in the
directions designated by F.
This helps to ensure injection jets discharged from nozzle holes
21A and 21B of each nozzle-hole set 22 through 27 are properly
collided, making it possible to promote atomization of fuel, and
broaden spray patterns 28 through 33 from nozzle-hole sets 22
through 27 into a wider area.
The operation of the fuel injection valve according to this first
embodiment will hereinafter be explained.
First, a magnetic field is formed by elements including valve
casing 2, fuel inlet pipe 3, and magnetic-path forming member 5
when electrical power is fed to electromagnetic coil 13 through
connector 15, and attraction portion 11 of valve element 9 is
magnetically attracted to an end surface of fuel inlet pipe 3.
As a result, valve portion 12 of valve element 9 lifts from valve
seat 8B of valve seat member 8, and valve element 9 opens against
the force of valve spring 16. Fuel within fuel passage 6 is
discharged from injection opening 8C of valve seat member 8 through
each nozzle-hole set 22, 23, 24, 25, 26, 27 of nozzle plate 18.
In this instance as shown by FIG. 6, injection jets of fuel ejected
from each nozzle hole 21A, 21B of nozzle-hole set 22 in the
directions designated by F collide with each other. Referring to
FIG. 5, fuel which is atomized by the collision of the injection
jets is discharged from nozzle-hole set 22 in spray pattern 28.
Fuel is discharged in the same manner from other nozzle-hole sets
23, 24, 25, 26, and 27 and atomized in spray patterns 29, 30, 31,
32, and 33, so that fuel discharged from each nozzle-hole set 22
through 27 is supplied to an engine intake manifold in a properly
intermixed condition (not shown).
Droplet diameter of fuel discharged from nozzle holes 21A and 21B
of colliding nozzle plate 18 according to the first embodiment will
be compared to that of a non-colliding nozzle plate with reference
to FIGS. 7 and 8.
First, as shown in FIG. 7, non-colliding nozzle plate 18' has a
plate thickness t equal to that of colliding nozzle plate 18
according to the first embodiment, and nozzle holes 21A' and 21B'
formed therein have a hole diameter d equal to that of nozzle holes
21A and 21B according to the first embodiment. However, nozzle
holes 21A' and 21B' are formed in nozzle plate 18' such that axes
A--A and B--B of respective nozzle holes 21A' and 21B' form an
upside-down V-shape. Nozzle holes 21A' and 21B' constitute a
non-colliding nozzle-hole set to diffuse injection jets of fuel in
differing directions without colliding them.
Droplet diameters of fuel discharged from nozzle holes 21A and 21B
of nozzle plate 18 and that of fuel discharged from nozzle holes
21A' and 21B' of nozzle plate 18' are compared, assuming hole
diameter d of nozzle holes 21A and 21B to be uniform with 21A' and
21B', where dimensional ratio t/d of plate thickness t and hole
diameter d varies according to plate thickness t of nozzle plates
18 and 18'.
A result for fuel discharged from nozzle holes 21A and 21B of
colliding nozzle plate 18 according to the first embodiment is
shown in FIG. 8 by characteristic line 34, which represents a
colliding injection. Here, droplet diameter becomes smaller the
larger the dimensional ratio t/d becomes between plate thickness t
and hole diameter d. In contrast, as shown by characteristic line
35 representing a non-colliding injection, droplet diameter of fuel
discharged from nozzle holes 21A' and 21B' of non-colliding nozzle
plate 18' becomes larger the greater dimensional ratio t/d
becomes.
In the range where dimensional ratio t/d is approximately 0.8, the
droplet diameter of fuel discharged from nozzle holes 21A and 21B
of colliding nozzle plate 18 according to the first embodiment is
substantially equal to that of non-colliding nozzle plate 18'.
However, when dimensional proportion t/d is greater than or equal
to 1.0, it is obvious that fuel is much more finely atomized when
compared with that of non-colliding nozzle plate 18'.
In this way, plate thickness t of nozzle plate 18 and hole diameter
d of nozzle holes 21A and 21B according to the first embodiment are
in a dimensional ratio t/d where the expression t/d.gtoreq.1.0 is
satisfied.
Thus, it is possible to make length L of nozzle holes 21A and 21B
formed in nozzle plate 18 larger, and to maintain the ability of
injection jets to travel in a straight line when fuel is discharged
from each nozzle hole 21A, 21B in the directions designated by
F.
It then becomes possible to properly collide injection jets
discharged from nozzle holes 21A and 21B of each nozzle-hole set 22
through 27, and to promote atomization of fuel. Accordingly, fuel
discharged from each nozzle-hole set 22 through 27 can be properly
intermixed by broadening spray patterns 28 through 33 into a wider
area, and more efficient combustion of fuel within an engine
combustion chamber is possible.
In the first embodiment plate thickness t of nozzle plate 18 (flat
portion 18A) is set within a range 0.3 mm.gtoreq.t.gtoreq.0.05 mm,
and hole diameter d of each nozzle hole 21A, 21B is set within a
range 0.3 mm.gtoreq.t.gtoreq.0.05 mm.
Therefore it is possible to form nozzle holes 21A and 21B in nozzle
plate 18 using a common hole-forming tool such as a drill, and it
is possible to contribute to a reduction in production cost for
nozzle plate 18.
A second embodiment according to the present invention will now be
explained referring to FIGS. 9 through 12. A feature of the second
embodiment rests in being applied to a fuel injection valve whose
casing is a magnetic cylinder.
A casing 41 is designed as an outer case of a fuel injection valve,
and includes a magnetic cylinder 42, a yoke 52, and a resin cover
55. In this instance, what was valve casing 2, fuel inlet pipe 3,
and joining member 4 in the first embodiment are integrally formed
as magnetic cylinder 42.
Magnetic cylinder 42 constitutes a main portion of casing 41, and
is a thin metal pipe formed with steps through such processing as
deep drawing of magnetic stainless steel or a similar material.
A base of magnetic cylinder 42 is formed with a larger diameter as
a large diameter portion 42A, an intermediary section extending
axially therefrom forms a mid-diameter portion 42B with a smaller
diameter than large diameter portion 42A, and an end extending
further axially therefrom forms a small diameter portion 42C with a
smaller diameter than mid-diameter portion 42B. The base of large
diameter portion 42A of magnetic cylinder 42 is joined to an engine
fuel conduit (not shown) or similar fuel supply.
A magnetic reluctance portion 42D is formed at a position axially
midway of small diameter portion 42C, the position coinciding with
a space S existing between a core tube 45 and an anchor portion 49
of a valve element 48. Therefore, both sections of small diameter
portion 42C axially on either side of magnetic reluctance portion
42D are substantially cut off magnetically by the provision of
magnetic reluctance portion 42D.
A fuel passage 43 is disposed within magnetic cylinder 42, and the
base of large diameter portion 42A forms a fuel inlet opening
thereof. Fuel passage 43 extends axially from the fuel inlet
opening as far as a valve seat member 47. A fuel filter 44 is
disposed at the base end of large diameter portion 42A to filtrate
fuel flowing into fuel passage 43 from a fuel conduit.
Core tube 45 is inserted within magnetic cylinder 42, and forms
part of a closed magnetic circuit generated by an electromagnetic
coil 54. Core tube 45 also serves to regulate how far valve element
48 may open. Core tube 45 is installed within mid-diameter portion
42B of magnetic cylinder 42 through press fitting, and an end
surface thereof faces an end surface of anchor portion 49 of valve
element 48. Space S exists between core tube 45 and anchor portion
49.
A spring bearing 46 is disposed within core tube 45 through press
fitting, and is formed in a thin tubular shape. A valve spring 51
is retained between spring bearing 46 and valve element 48, and
since spring bearing 46 is press-fitted within core tube 45, it is
possible to adjust a spring force of valve spring 51 according to
how deeply spring bearing 46 is press-fitted with respect to core
tube 45.
Valve seat member 47 is disposed within small diameter portion 42C
of magnetic cylinder 42 on a side of valve element 48 opposite core
tube 45. As can be seen from FIG. 10, valve seat member 47 is
formed as a cylindrical shaft defining a valve element insertion
hole 47A. A valve seat 47B is disposed on an inner circumference of
valve seat member 47, and defines an injection opening 47C in
substantially the same manner as the first embodiment. Valve seat
member 47 is press-fitted within small diameter portion 42C of
magnetic cylinder 42, and is welded about an entire outer
circumference thereof to small diameter portion 42C. A nozzle plate
57 is welded to an end surface of valve seat member 47 to cover
injection opening 47C.
Valve element 48 is contained within small diameter portion 42C of
magnetic cylinder 42, between core tube 45 and valve seat member
47, and is axially displaceable therein. Valve element 48 comprises
anchor portion 49 which is formed in a stepped tube shape and made
from a magnetic metallic material, and a valve portion 50 which is
spherical and fixed to an end portion of anchor portion 49. Valve
portion 50 rests on or lifts from valve seat 47B of valve seat
member 47.
Valve portion 50 of valve element 48 is normally held in a resting
state on valve seat 47B of valve seat member 47, and in this state
space S is formed axially between the end surface of anchor portion
49 and the end surface of core tube 45. When electrical power is
fed to electromagnetic coil 54, anchor portion 49 is magnetically
attracted to core tube 45, whereby valve element 48 opens as a
result of valve portion 50 lifting from valve seat 47B of valve
seat member 47 against the spring force of valve spring 51.
Valve spring 51 is disposed between spring bearing 46 and valve
element 48, and normally applies force to valve element 48 in a
closed-valve direction (direction in which valve portion 50 rests
on valve seat 47B of valve seat member 47). The spring force of
valve spring 51 can be adjusted according to how deeply spring
bearing 46 is press-fitted with respect to core tube 45.
Yoke 52 is disposed on an outer circumference of magnetic cylinder
42, is formed in a stepped tube shape and made from a magnetic
metallic material, and constitutes a portion of casing 41. Yoke 52
is fixedly press-fitted to an outer circumference of small diameter
portion 42C of magnetic cylinder 42. A connecting core 53 is
disposed between mid-diameter portion 42B of magnetic cylinder 42
and yoke 52, and is formed from a magnetic material substantially
in a C-shape around the outer circumference of mid-diameter portion
42B.
Electromagnetic coil 54 is disposed between magnetic cylinder 42
and yoke 52 as an actuator, and is mainly comprised of a coil form
54A formed from resin material in a tube-shape, and a coil 54B
wound about coil form 54A. An inner circumference of coil form 54A
is attached to mid-diameter portion 42B of magnetic cylinder
42.
When electromagnetic coil 54 is electrically energized, small
diameter portion 42C of magnetic cylinder 42, core tube 45, anchor
portion 49 of valve element 48, yoke 52, and connecting core 53
form a closed magnetic circuit. Anchor portion 49 of valve element
48 is magnetically attracted by core tube 45 due to the closed
magnetic circuit passing through space S existing between core tube
45 and anchor portion 49 of valve element 48.
Resin cover 55 is disposed on the outer circumference of magnetic
cylinder 42, and in a state where elements including yoke 52,
connecting core 53, and electromagnetic coil 54 are assembled on
the outer circumference of magnetic cylinder 42, a connector 56 is
formed integrally therewith on an outer surface thereof using a
means such as injection molding.
Therefore when electromagnetic coil 54 is electrically energized
via connector 56, valve element 48 opens, and fuel supplied to fuel
passage 43 within magnetic cylinder 42 is injected into an engine
intake manifold through injection opening 47C of valve seat member
47, and then through nozzle plate 57.
As shown in FIGS. 10 through 12, nozzle plate 57 covers injection
opening 47C of valve seat member 47 on an outer side thereof.
Nozzle plate 57 is formed from a material such as circular metal
plate with a predetermined thickness, and is joined to the end
surface of valve seat member 47 by means of welding portion 58 in a
manner substantially the same as the first embodiment.
A plurality of nozzle holes 59 is disposed centrally in nozzle
plate 57. Two adjacent holes 59A and 59B constitute a hole set,
there being six nozzle-hole sets 60, 61, 62, 63, 64, and 65 in a
manner substantially the same as the first embodiment. The hole
diameter, angle of inclination, displacement, and other attributes
of nozzle holes 60 through 65 are set in substantially the same
manner as the first embodiment, and such that the aforementioned
formula and conditions are satisfied.
Nozzle plate 57 is formed as a colliding nozzle plate, and
injection jets of fuel discharged from respective nozzle holes 59A
and 59B of nozzle-hole sets 60 through 65 are collided with one
another.
In this manner, it is possible to achieve results with the present
second embodiment which are substantially the same as those of the
first embodiment, and furthermore, it is possible to apply
colliding nozzle plate 57 to a fuel injection valve comprising
magnetic cylinder 42.
This application is based on prior Japanese Patent Applications
Nos. 2003-023128 and 2002-157919. The entire contents of Japanese
Patent Application No. 2003-023128 with a filing date of Jan. 31,
2003, and Japanese Patent Application No. 2002-157919 with a filing
date of May 30, 2002, are hereby incorporated by reference.
Although the invention has been described above by reference to
certain embodiments of the invention, the invention is not limited
to the embodiments described above. Modifications and variations of
the embodiments described above will occur to those skilled in the
art in light of the above teachings. The scope of the invention is
defined with reference to the following claims.
For example, from two to five sets, or seven or more sets of nozzle
holes may be formed. Also, a nozzle-hole set may comprise as many
as three or perhaps four holes.
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